Make the soup
Combine 10 cups water and all remaining soup ingredients except gelatin in large pot. Bring to boil, spooning off any foam that rises to surface. Reduce heat and simmer, uncovered, until chicken pieces are very soft and beginning to fall apart, adding more water by cupfuls if necessary to keep chicken submerged, about 2 hours 30 minutes.

Make the sauce
Mix 1 cup black vinegar, 6 tablespoons soy sauce, and 2 tablespoons fresh ginger strips in small bowl. DO AHEAD Can be made 1 day ahead. Cover and refrigerate. Bring to room temperature before serving.

Make the filling
Combine all filling ingredients in large bowl and mix with fork just until blended. Cut aspic into 1/3-inch cubes. Add aspic to pork mixture; stir gently with wooden spoon just until incorporated. DO AHEAD Can be made 1 day ahead. Cover and refrigerate.

Assemble the dumplings
Line 2 rimmed baking sheets with parchment paper. Place 1 dumpling wrapper on work surface. Spoon 1 very generous teaspoon filling onto center of wrapper, including at least 2 or 3 aspic cubes.

Pleat the wrapper
Lightly brush edges of dumpling wrapper with water. Bring 1 corner of wrapper up around filling, then pleat remaining edges of wrapper at regular intervals all around filling until filling is enclosed and wrapper forms bundle-like shape with small opening at top.

Twist the top
Gather top edges of wrapper together and twist at top to enclose filling. Place on baking sheet. Repeat with remaining wrappers and filling. DO AHEAD Can be refrigerated, covered, for 1 day, or frozen in single layer in covered containers for 2 weeks.

Prepare the steamer
Line each layer of bamboo steamer basket with cabbage leaves; place over wok filled with enough water to reach just below bottom of bamboo steamer basket. (Or line metal steamer rack with cabbage leaves and set over water in large pot.) Place dumplings atop cabbage, spacing apart.

Steam the dumplings
Bring water to boil. Cover; steam until cooked through, adding more water to wok if evaporating too quickly, about 12 minutes for fresh dumplings and 15 minutes for frozen. Serve dumplings immediately, passing sauce alongside for dipping.